Ok.... at the top of my list for root cause possibilities is the following:truman said:Quote:This makes sense to me and would explain why failure is sudden and catastrophic. The followup question would be how and why could a fuel starvation/lubrication condition occur at the cam roller interface?
Based on the design, its seems that VW took great pains to supply fuel to the cam/roller chamber and the HPFP (3 pumps in the fuel system - amazing). In fact, there are enough sensors to put the engine in "emergency mode" (page 37) giving me the impression that VW will not allow the engine to be run hard without the fuel system running as intended. So, instead of fuel starvation I'm thinking that the fuel used in the failed pumps does not have enough lubricity. I've stated this in other posts (see below - post #105), but the more I look into this issue the more a fuel additive seems required to minimized the potential for HPFP failure. We should not have to use an additive, but unless you can verify that the majority of fuel you use has a lubricity with an HFRR value of <460 microns you should use an additive. US fuel specification is <520 microns. See the following thread for more info on HFRR values.